Device, system and method for monitoring and communicating biometric data of a diver

ABSTRACT

A system and method for monitoring biometric data of a diver and signaling those data from a first communication device to other communication devices, e.g., those of other divers, on a ship or buoy. A signal generated from a device of the diver can generate a diver identifier, an indication of a stress state of the diver and the diver&#39;s location.

RELATED APPLICATIONS

This application claims priority to provisional U.S. patent applicationSer. No. 61/384,612, filed Sep. 20, 2010, which is hereby incorporatedby reference in its entirety for all purposes.

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/231,881, filed Sep. 13, 2011; which claims benefit ofpriority to (i) provisional U.S. patent application No. 61/382,438,filed Sep. 13, 2010, and to (ii) provisional U.S. patent application No.61/384,612, filed Sep. 20, 2010; all of the aforementioned priorityapplications being hereby incorporated by reference in their respectiveentireties for all purposes.

FIELD OF THE INVENTION

Embodiments described herein relate to a system for monitoring a diver.More specifically, embodiments described herein relate to a system formonitoring and communicating biometric data of a diver such as heartrate or blood oxygen saturation.

BACKGROUND

SCUBA (Self-Contained Underwater Breathing Apparatus) diving is becomingan increasingly popular activity both for recreation and in variousindustrial applications (e.g., underwater welding, oil rig repair,salvage, etc.). There are a number of health risks associated with SCUBAdiving due to the underwater environment in which divers operate and thesubsequent effect on their physiology. These include hypoxia,hypercapnia, embolism, the “bends”, nitrogen narcosis, pressure inducedarrhythmias and lung expansion injury. Many of these conditions canoccur or enter a precursor state with little or no apparent warning tothe diver. While divers can be trained to recognize the symptoms, theyoften don't or choose not to. While there are portable devices the divercan take with them to monitor physiological indicators of thesesymptoms, the diver often is not vigilant enough in monitoring theindicators (being preoccupied with the dive), the conditions develop tooquickly or they are not provided with the indicators for particularconditions, such as hypoxia, in a form they can readily discern. What isneeded is a system for monitoring a diver's biometric data andtransmitting that data so that indicators of physiological distress andother conditions can be analyzed by others without distraction. What isalso needed is a system for monitoring particular biometric dataincluding data more indicative of particular adverse physiologicalconditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an embodiment of the biometric data communicationsystem.

FIG. 1B illustrates an embodiment of a portable underwater monitoringdevice such as a PDA-like device.

FIG. 2 is a lateral view of an embodiment of a system including a sensordevice for optically measuring blood oxygen or other blood gassaturation of a diver.

FIG. 3A is a cross sectional view of an embodiment of the sensor devicehaving an elastic band with the emitter and detector configured forreflectance oximetry.

FIG. 3B is a cross sectional view of an embodiment of the sensor devicehaving an elastic band with the emitter and detector configured forabsorbance oximetry.

FIG. 4 is a lateral view showing an embodiment of a sensor deviceincorporated into a diver's glove.

FIG. 5 is a lateral view showing an embodiment of a monitoring devicehaving an internal sensor device for optically measuring blood oxygen orother blood gas saturation of a diver.

FIG. 6 is a block diagram showing a configuration of various modulesoperating on an embodiment of the monitoring device processor.

DETAILED DESCRIPTION

Embodiments described herein provide a system and method for monitoringvarious biometric data (e.g., heart rate, blood gases, etc.) of a diverand signaling the data from a first communication device which isunderwater to another communication device on a surface platform such asa floating buoy. In many embodiments, the communication device can beprovided by a mobile or portable device (e.g., handheld device such ascellular messaging/telephony or personal digital assistant) which caninclude a processor, display and user input device such as a touchscreen. The communication device can include (inherently or by way ofaccessory functionality) an acoustical transducer, for example, anultrasonic transducer comprising a piezoelectric material. The processoris configured to monitor various physiological data including heartrate, respiration rate, blood pressure, blood oxygen saturation andother blood gas measurements. The communication device may alsoimplement one or more algorithms which use such data to determine if thediver is in a state of physiologic stress (e.g. such as that caused byblood oxygen levels or out gassing of nitrogen, causing the “bends”) ora state preceding or otherwise predictive of a state of physiologicalstress.

According to embodiments, when such a state or precursor state of stressis detected, the first communication device communicates information(e.g. notification, message etc.) to one or more other communicationdevices to allow other individuals (such as those on a dive boat orother monitoring craft or even those onshore) to monitor the diver(s)and/or alert them when it is time to take action (e.g., have the diversascend and/or provide assistance to the divers).

In one embodiment, the first communication device can send out anacoustical distress signal to the communication device of any otherdiver in the vicinity when the diver is in a precursor or state ofphysiologic stress. The signal can include various information includingan identifier of the particular diver, the particular state he or she isin and the location of the diver (either absolute and/or in relation tothe floating buoy, dive boat or other craft).

Other embodiments provide a device, system and method for (i) measuringor otherwise determining blood oxygen or other blood gas saturation of adiver while he or she is underwater, and then (ii) convertingmeasured/determined data an acoustic signal for transmission to anacoustical communication device. The system can include a watertightmonitoring device, which can be a portable or mobile device worn by thediver. The device may be coupled to a sensor device either directly orwirelessly for example, using RF communication. The sensor device cancomprise a band or strip worn over an extremity such as a finger or toe.In one implementation, the device has an optical emitter and detector toemit and detect light. Information detected from the sensor can be usedto determine, for example, an absorbance which is correlative orotherwise corresponding to a blood oxygen saturation of the diver usingoximetry methods known in the art.

Among other variations, the band or strip can be held in place using aclip, clamp, or a resilient sleeve worn over the finger or toe and canalso include other configurations for holding the sensor device at adesired location on or adjacent the diver's body. In one embodiment, thesensor device, including the band or strip, may be incorporated into asection of the finger covering of a glove worn over the diver's hand.

In one embodiment, the monitoring device can include an RF communicationdevice for receiving an input from the sensor device, and a processorconfigured to control the intensity, duration, frequency or othercharacteristic of an optical signal from the emitter. The processor mayalso implement a process for (i) calculating blood saturation levelsfrom the inputted optical signal (e.g., calculation module), (ii)converting the measured blood oxygen saturation or other informationinto an acoustical signal (e.g., “a signal processing module”), (iii)creating an ID signal used to identify the diver and controlling thetransmission of the acoustical signal (e.g., “a communications module”)and (iv) monitoring the devices and/or divers.

According to some embodiments, the one or more processors may implementa process or alarm module for determining when the diver's blood oxygensaturation is too low or otherwise indicating that the diver is in astate of distress and a master control module for controlling thefunctions of one or more of the preceding modules.

Various embodiments described herein use devices that are carried by orwith divers. These devices may be made of various design, form factorand/or platform. In some embodiments, the devices are specialty devices,configured logically and structurally for use with divers. In otherembodiments, the devices are configured or reconfigured devices havingprimary or past functionality in the form of messaging, cellularcommunications (e.g. smart phone) or personal information management(PIM). In some embodiments, the devices are accessorized to includecomponents with functionality as described. For example, attachmentmodules to existing handsets may carry components as described by someembodiments. Still further, the devices may be carried as handsets orworn by the divers (e.g. wrist watch, computerized necklace, wristbandor headband etc.).

As used herein, the terms “acoustic” and “acoustical” are usedinterchangeably. Referring now to FIGS. 1A-1B, various embodimentsprovide a system 300 and methods for monitoring various biometric data(e.g., heart rate, blood gases, etc.) of a diver 310 and signaling thosemeasurements from a first communication device 320 worn or carried bythe diver 310 to another communication device 330 which may beunderwater or positioned on a surface platform 340, which in manyembodiments, corresponds to a floating buoy 350. In various embodiments,buoy 350 can be a self-propelled buoy 350 having a propulsion controlsystem for staying within an effective communication range of diver 310.Further description of various embodiments of self propelled buoys isfound in U.S. Provisional Patent Application Ser. No. 61/382,438 andU.S. patent application Ser. No. 13/231,881 which are both fullyincorporated by referenced herein. In many embodiments, the firstcommunication device 320 can be incorporated into a watertight portablemonitoring device 360. Portable monitoring device 360 will typicallycomprise a PDA like device 360 that is worn or carried by diver 310.Device 360 may also comprise, or be integrated into, a dive watch, divecomputer or other device or equipment carried by the diver, e.g., aflash light, depth gauge, regulator, etc. For ease of discussion, device360 will now be referred to as PDA 360; however, other embodiments areequally applicable. PDA 360 includes a processor 370, display 380, userinput means 385, and an electrical power source 365. Power source 365may correspond to a portable battery, such as a lithium or lithium ionbattery, or other battery chemistry known in the art. Display mean 85may correspond to a touch screen which may be separate or integral withdisplay 380. Processor 370 includes one or more modules 390 forcontrolling various operations of device 360 including those ofcommunication device 320 as will be explained further herein.

Communication devices 320 and 330 can comprise one or more acousticaltransducers 321 which transmit and/or receive acoustical energy at aselected frequency or range of frequencies. Acoustical transducers 321may correspond to one or more ultrasonic transducers 322 which cancomprise various piezoelectric materials such as piezo-electric ceramicmaterials. The particular acoustical transducer 321 and acousticalfrequency can be selected based on the desired acoustical transmissionrange, acoustical sensitivity, bandwidth, maximum diving depth,temperature and salinity conditions, and related parameters. In variousembodiments, the acoustical frequencies used by devices 320 and 330 (orother similar device) can be in the range of about 20-150 kHz, morespecifically, in the range of about 50-125 kHz and still morespecifically, in the range of about 70-100 kHz. Other ranges are alsocontemplated. The specific range can be selected depending upon one ormore factors such as the expected ambient conditions (e.g. temperature),expected depth, desired bandwidth of data, and desired communicationrange. Also, acoustical transducers 321 may be configured as bothacoustical transmitters and receivers so as to send and receiveacoustical signals. In many embodiments, transducers 321 can be arrangedas an array 323 of transducers which may include a phased arrayformation. Array 323 can be configured to optimize one or more of thetransmission range, sensitivity, and bandwidth of communication device320. Larger arrays 323 (e.g., a greater number of transducers, and/orspread out over a larger area) can be used to increase sensitivity andtransmission distance. In particular embodiments, the communicationdevices 320 from multiple divers 310 can be used to form an array 323having increased sensitivity and transmission range.

The processor 370 will typically correspond to one or moremicroprocessors known in the art and can be selected for increaseddurability, fault tolerance, and pressure resistance for underwateroperation, using various MIL-SPEC criteria known in the military/navalequipment arts. Processor 370 will typically include one or more modulesor algorithms 390 for computing, monitoring, and communicating variousphysiological data of diver 310 including for example, heart rate,respiration rate, blood pressure, blood oxygen saturation and otherblood gas measurements (e.g., blood nitrogen). It may also include othermodules 390 which use such data to determine if the diver is in a stateof physiologic stress (e.g., such as that caused by low blood oxygenlevels, (e.g., “hypoxia”) or out gassing of nitrogen, causing the“bends”) or a precursor state which precedes or is otherwise predictiveof a state of physiological stress. When such a stress state orprecursor state of stress is detected, it may be communicated by thefirst communication device 320 to the second communicative device 330 toallow other individuals (such as those on the dive boat or even thoseonshore) to monitor the diver(s) and alert them when it is time toascend and/or if diver requires assistance.

In one embodiment, the first communication device 320 can send out anacoustical distress signal 325 when the diver is in a precursor and/orstate of physiologic stress. Signal 325 can include various informationincluding an identifier of the particular diver, the particular statethe diver is in, and the location of the diver. The signal 325 can beconfigured to reach not only communication device 330 on the watersurface (such as that in the buoy, dive boat or monitoring ship) butalso the communication device 330 of any other diver in the vicinity. Inparticular embodiments, signal 325 may be sent at a different acousticalfrequency or range of frequencies from that normally used bycommunication devices 320 and 330 such that: i) persons or equipmentmonitoring communications from the devices will immediately know thatthere is a diver in a distress; and ii) there is little or nointerference from other acoustical communication between devices 320 and330. Further, signal 325 may also include a priority or over-ride signalsent at the beginning of 325 which puts all other communication devices330 into a listening mode for a select period of time (e.g., up to oneminute or longer) so as to assure no interference from signals sent byother devices 330 and thus improve the ability of other devices 330 fordetecting distress signal 325 as well as the transmission range ofsignal 325 (e.g., by improving its signal to noise ratio). The prioritysignal can be sent at a different frequency or range of frequencies thanthat normally used by devices 320 and 330.

Referring now to FIGS. 2 and 3A-5 other embodiments also provide adevice 410, system 400 and method for measuring blood oxygen saturation(or other blood gas) of a diver 310 while he or she is underwater andthen convert that measurement into an acoustic signal for transmissionto an acoustical communication device described herein. System 400 caninclude a watertight monitoring device 460 such as a PDA-like device 460(herein PDA 460) worn or carried by the diver 310 that is coupled to asensor device 410. PDA 460 may be one in the same as PDA 360 and in manyembodiments may comprise or otherwise be incorporated into a dive watchor like device that is worn on the diver's wrist or arm. PDA 460 may becoupled to sensor device 410 either directly for example, using aconnector 416 (such as a cable or wire) or wirelessly for example, usingmagnetic communication as is described below.

Sensor device 410 can comprise a support layer 411, an optical emitter412 and optical detector 413 and an electrical power source 419 such asa lithium button battery or other miniature battery known in the art.Support layer 411 may correspond to a band, strip or cuff 411 that isworn over a site on the diver's skin, typically, an extremity E such asa finger F or toe. For ease of discussion, support layer 411 will now bereferred to as a band 411. Band 411 has an optical emitter 412 (whichmay correspond to one more LED's of the same or different wavelengths)and optical detector 413 (which may correspond to one or morePhotodiodes) that are selected and arranged to emit and detect light ofat least one wavelength having an absorbance which is correlative orotherwise corresponding to a blood oxygen saturation level (or otherblood gas) of the diver using oximetry methods known in the art. Inparticular embodiments, the wavelength can include at least a first andsecond wavelength with larger numbers considered. Additionally, theemitted light can also include a reference signal having an absorbancewhich is only minimally effected by the oxygen saturation level of thedivers blood. The emitter and detector 412 and 413 are waterproofed andselected and configured to withstand the pressures of the dive. Emitterand detector 412 and 413 can be configured for reflectance type orabsorbance type oximetry. For embodiments using reflectance typeoximetry, the emitter(s) and detector(s) are placed proximate each otheron the same side of the diver's skin as is shown in the embodiment ofFIG. 3A. For embodiments using absorbance type oximetry, the emitter anddetector are placed on opposite sides of the skin on an area of the skinthat has good blood flow and fairly translucent (such as the finger orearlobe) as is shown in the embodiment of FIG. 3B. For eitherembodiment, the intensity and other optical characteristic of the lightemitted by emitter 412 can be modulated or otherwise adjusted forunderwater conditions, such as depth, water temperature, or opticalproperty of the water the diver is in. For example, the intensity of theemitted light can be modulated with respect to the diver's depth(measured e.g., by means of an electronic depth gauge that isoperatively coupled to device 410 and/or PDA 460). Higher intensitiescan be used for deeper depths due to fact that the higher waterpressures at deeper depths may cause blood normally present in the upperlayers of the skin to be forced away from the skin surface into deepertissue. Thus a stronger intensity may be needed to penetrate deeper intothe skin and subjacent tissue where sufficient blood is present to makean oximetry measurement. Correlations can be developed between requiredsignal strength and diving depth using known mathematical modelingand/or laboratory testing and models (e.g., least squares, cubitspline). In various embodiments, the intensity of light from emitter 412can be adjusted linearly, logarithmically or other manner with respectto depth (e.g., in a first or second order manner). A similar situationmay occur for colder water temperatures, where, due to vasoconstrictionof the skin, from colder temperatures, blood is forced away from theskin, requiring higher intensities. Also higher intensities can be usedto compensate for losses in intensity of the incident orreflected/transmitted light from the skin due to the presence of waterand various particulate matter in the water (e.g., due to scattering,reflectance etc.). In this latter case, a calibration signal may be sentto compensate for the presence of water, e.g., before emitter 412 emitsan optical signal 412s used for measurement of blood oxygen saturation.Alternatively, a dual beam approach can be used for optical signal 412swith one beam directed at the diver's skin the other into any water nearthe diver's skin.

The emitter and detector 412 and 413 can be integral or otherwiseattached to band 411 such that they face into the skin surface. They mayalso be recessed within band 411 so that they will be pressed into theskin by embodiments having a resilient/elastic band 411 and/or the forceof surrounding water pressure and thus improve or optimize thewatertight seal between band 411 and the skin as they do not create anygaps or protuberances between the band and the diver's skin. Band 411 isconfigured to form a watertight seal with the particular extremity(e.g., appendage) it is worn over. Accordingly, band 411 can be held inplace using an attachment feature 415 such as a clamp, clip, VELCRO areaor an elastic sleeve worn over band 411 at least a portion of the fingeror other extremity E. Band 411 itself may comprise an elastic sleeveworn over the finger or other extremity E. In one embodiment, the sensordevice 410 including the band 411 may be incorporated into a section ofthe finger covering of a glove worn over the diver's hand as is shown inthe embodiment of FIG. 4. Other embodiments contemplate a number ofconfigurations for band 411 so that it may place position emitter anddetector 412 and 413 or other sensor device 410 on or adjacent thediver's body.

The PDA device 460, can include an acoustic communication device 420, amagnetic communication device 461 for receiving an input from the sensordevice 410, a processor 470, display 480 a user input means 485 such asa touch screen and a power source 465 for powering various components ofthe PDA as well as the sensor device 410. In one or more embodimentspower source 465 may correspond to a chemical battery such as lithium,lithium ion, or other battery chemistry known in the art. Magneticcommunication device 461 is configured for receiving an input frommagnetic communication device 417, and a microprocessor 470 (which canhave similar properties as microprocessor 370) having one or moremodules 490 for performing one or more operations relating to thecalculation, processing and communication of various biometric data.

In an alternative or additional embodiment, PDA 460 may also include aninternally based sensor device 410 comprising an internal compartment orchamber 466 having emitter and detector 412 and 413 and configured forinsertion of the diver's finger as is shown in the embodiment of FIG. 5.Chamber 466 will typically include a gasket or other water tightflexible seal 469 attached to the wall of the PDA through which thediver inserts their finger. The internal wall 467 of chamber 466 maycomprise a compressible sealing liner 468, such as an elastomer(silicone, polyurethane, etc.), that is conformal to the contour of thediver's finger. The internal diameter of chamber 466 with sealing liner468 in place is configured such that the sealing liner compressesagainst the diver's finger and, in this way, assures that the diver'sskin is flush against emitter and detector 412 and 413 and eliminatingor minimizing any water between the diver's skin and the emitter anddetector.

For embodiments of system 400 using magnetic communication, sensordevice 410 and PDA 460 can each include magnetic communication devices(also referred to as transceivers) 417 and 461 respectively for sendingand receiving a magnetic signal 418. Such devices can comprise amultichip (or hybrid chip) coupled to a magnetic coil. The multichip canbe configured to function both as a transmitter and receiver andtypically comprises a macro controller chip, op-amps, eproms and otherelectronic circuits. The antenna coil is tuned to thetransmission/carrier frequency and can range from 5 kHz to about 150kHz, with an preferred range of 30 to 50 kHz and a specific example ofabout 38 kHz. The multichip generates a signal 418 in the form of amagnetic field 418F which is transmitted and received by the antennacoils. The magnetic field has a strength which falls off by the squareof the distance. The effective transmission distance between the devicesis a function of transmission power, receiver noise, and sensitivity.The transmission is encoded and modulated, typically in a pulse periodor other fashion so as to conserve power. In the receiver mode, themultichip amplifies and decodes the pulse position pulsed data.Transmission bursts may occur at regular intervals, for example, every 5seconds. After receiving and decoding a valid burst, the receiver shutsdown, conserving power, and only wakes up just prior to when the nextburst is expected. In this way, transmitter and receiver power may beminimized or otherwise reduced.

As described above, processor 470 can include a variety of modules oralgorithms 490 for controlling various functions of system 400.Referring now to FIG. 6, in various embodiments, modules 490 can includeone or more of an optical control module 491 for controlling theintensity, duration, frequency or other characteristic of an opticalsignal 412s emitted from emitter 412, a magnetic communication module,for controlling embodiments of system 400 employing magneticcommunication (e.g., using a signal 418) between sensor device 410 andPDA 460, a calculation module 493 for calculating blood oxygen (or otherblood gas) saturation levels using a signal 413s received from detector413, a signal processing module 494 for converting the measured bloodoxygen saturation or other information into an acoustical signal 500, anidentifier module 495 for creating an ID signal 510 used to identify thediver, a communications module 496 controlling the transmission of theacoustical signal 500 and a monitoring or alarm module 497 fordetermining when the diver's blood oxygen saturation is too low orotherwise indicating that the diver is in a state of distress and amaster control module 498 for integrating and controlling the functionsof one or more of the preceding modules.

In use, measurement and communication of blood oxygen saturation bysensor device 410 and system 400 allows the diver (and those monitoringthe diver) to be alerted when the diver is at the earliest stages ofhypoxia, and/or precursor states of hypoxia. This allows the diver totake various actions, (e.g., going back to the surface, checking theirdiving gear, adjusting their regulator, communicating with other diversor those on the surface, etc.), before the further onset of hypoxia andpotentially any life threatening conditions. It also allows other diversand/or those on the surface to quickly come to the aid of the diver ifnecessary. Similarly, for embodiments of sensor device 410 configuredfor measurement of blood nitrogen saturation, the diver or thosemonitoring the diver may take various appropriate actions before thedevelopment of the “bends.” In particular embodiments, PDA device 460can be configured to alert the diver when their blood nitrogensaturation is too high (which increases the conditions likely fordevelopment of the bends) and/or there is a threshold decrease, or rateof decrease of blood nitrogen saturation (implying that nitrogen iscoming out of solution, a beginning or early event in the development ofthe bends). Additionally, such measurements may also be used to assistthe diver in making their ascent back to the surface. For example, insome embodiments, system 400 (via use of modules 490, display 480 and/orcommunication device 420) can be configured to assist the diver inmaking their ascent by providing visual or audio cues or otherinformation to the diver to remain at a particular depth for aparticular period of time, and/or to ascend at a particular rate. Inthis way, the system 400 allows the diver to make a controlled ascentwhich reduces the likelihood of the development of the bends. In variousembodiments, these assist signals can also be sent out concurrent towhen the system has determined when the diver is a in a precursor stateand/or state of physiological stress, e.g., hypoxia etc.

Conclusion

The foregoing description of various embodiments have been presented forpurposes of illustration and description. It is not intended to limitthe invention to the precise forms disclosed. Many modifications,variations and refinements will be apparent to practitioners skilled inthe art. For example, various embodiments of the monitoring system canbe adapted for salt and fresh water environments, as well as deep dives(e.g., 60 to 200 meters) and cold water environments. They may also beadapted for use in closed circuit re-breathers in addition to standardSCUBA equipment. Additionally, they may be adapted for measurement andmonitoring of a number of biometric data including a number of bloodgases including oxygen, carbon dioxide, nitrogen and helium.

Elements, characteristics, or acts from one embodiment can be readilyrecombined or substituted with one or more elements, characteristics oracts from other embodiments to form numerous additional embodimentswithin the scope of the claimed embodiments. Moreover, elements that areshown or described as being combined with other elements, can, invarious embodiments, exist as standalone elements. Hence, the scope ofthe described embodiments is not limited to the specifics of thedescription, but is instead limited solely by the appended claims.

What is claimed is:
 1. A method for monitoring a blood gas saturationlevel of a diver, the method comprising: emitting an optical signal intowater near the diver while the diver is underwater; detecting theoptical signal; determining an underwater condition based on thedetected optical signal; emitting light into the diver's skin at awavelength having an absorbance associated with the blood gas saturationlevel, the intensity of the light modulated responsive to at least thedetermined underwater condition; detecting an intensity of a reflectedor transmitted light from the diver's skin; and determining the bloodgas saturation level of the diver utilizing the detected intensity. 2.The method of claim 1, wherein the light is emitted into the skin whilethe diver is wearing one or more pieces of SCUBA equipment.
 3. Themethod of claim 1, wherein the intensity of the emitted light is furthermodulated responsive to a depth of the diver.
 4. The method of claim 1,wherein the intensity of the emitted light is further modulatedresponsive to a water temperature.
 5. The method of claim 1, wherein theintensity of the emitted light is further modulated responsive to awater salinity.
 6. The method of claim 1, wherein the intensity of theemitted light is modulated responsive to a light absorbance of waternear the diver's skin.
 7. The method of claim 1, wherein the blood gassaturation is a blood oxygen saturation, the method further comprising:alerting the diver when the blood oxygen saturation level is at or belowa threshold level.
 8. The method of claim 7, wherein the threshold levelis about 95% saturation.
 9. The method of claim 7, wherein the thresholdlevel is about 90% saturation.
 10. The method of claim 1, furthercomprising: generating an acoustical signal including information on theblood gas saturation level, the acoustical signal configured to betransmitted underwater; and transmitting the acoustical signal from afirst communication device proximate the diver to a second communicationdevice.
 11. The method of claim 10, wherein the second communicationdevice is positioned at or near the water surface.
 12. The method ofclaim 11, wherein the second communication device is positioned on abuoy.
 13. The method of claim 12, wherein the buoy is self-propelled andincludes a control system configured to maintain the buoy within aneffective communication range of the first communication device.
 14. Themethod of claim 1, further comprising: generating a low power magneticsignal including information on the blood gas saturation level, themagnetic signal configured to be transmitted underwater; andtransmitting the magnetic signal from a first magnetic communicationdevice to a second magnetic communication device.
 15. The method ofclaim 14, wherein the first magnetic communication device is containedin a sensor device positioned near the diver's finger.
 16. The method ofclaim 14, wherein the second magnetic communication device is containedin a dive watch.
 17. The method of claim 14, wherein the first magneticcommunication device is contained in a sensor device positionedproximate to the diver's finger.
 18. The method of claim 14, wherein thefirst and second magnetic communication devices are positioned withinabout six inches of each other.
 19. The method of claim 14, furthercomprising: converting the lower power magnetic signal into anacoustical signal including information on the blood gas saturationlevel, the acoustical signal configured to be transmitted underwater;and transmitting the acoustical signal from a first acousticalcommunication device proximate the diver to a second acousticalcommunication device.
 20. The method of claim 1, wherein the conditionis an optical property of water near the diver or a particular contentof water near the diver.
 21. A method for monitoring a blood gassaturation level of a diver, the method comprising: emitting an opticalsignal into water near the diver while the diver is underwater;detecting the optical signal; determining an underwater condition basedon the detected optical signal; emitting light into the diver's skin ata wavelength having an absorbance associated with the blood gassaturation level, the intensity of the light modulated responsive to thedetermined underwater condition and at least one of a depth of the diveror, a water salinity; detecting an intensity of a reflected ortransmitted light from the diver's skin; and determining the blood gassaturation level of the diver utilizing the detected intensity.
 22. Themethod of claim 21, wherein the condition is an optical property ofwater near the diver or a particular content of water near the diver.